The inverted anchor drag

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Jamesuk

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The inverted anchor drag Delta

Anyone ever had an inverted anchor drag when the pull On the anchor changed direction by 180 degrees in sand before? (Non tidal)

I popped into Palma Yacht Centre where they have a lovely sand pit and it would seem 'ALL' similar anchors to the Delta failed including the new Ultra with swivel.
 
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Not unusual - Particularly in a soft seabed - this is one reason Fortress are good in soft mud.

Many anchors need a hard seabed to set, think of a roll bar or Delta's roll over shank (that virtually every anchor maker uses - Spade included). They need a hard seabed on which to rest. Turn them upside down and submerge them is something soft, think custard?, or soft sand, mud and they have nothing on which to rest and roll over. Their centre of gravity is too low and they will drag, and drag and drag - until you reach the beach, or somewhere with a harder substate.

I did some tests on set anchors - upto about 150 degrees anchors will turn in the seabed. beyond 150 degrees they will somersault, land on their back and then need to reset.

It depends on the rate of turn but if your yacht passes beyond that, approx, 150 and then the tension is sufficient - your anchor will somersault.

Set it hard, with a tension higher than the tension the tide might impose - and you should stay where you are/were - otherwise?

The idea there is one perfect anchor, a myth put about by anchor makers.

Jonathan
 
I don't know what you mean by an "inverted anchor". My anchor is all hollow and lightweight on top, and filled with lead on the bottom, so it seems quite unlikely that it would turn upside-down. If lying on its side, any pull on the shank causes it to roll the tip into the surface - even my living room rug when it was first delivered!

Pete
 
I have to assume your rug sits on floorboards, carpet (concrete would be unusual) but not custard :)

I watched an anchor drag through soft sand (inverted), shank completely buried and fluke sitting on the custard, sorry soft sand - it does happen.

edit, but seriously - I cannot comment on one with a hollow shank and lead in the toe - I have not see one dragged upside down across the seabed - but if it works for you and you are comfortable, ignore my final sentence. close edit

And you might be sceptical but its not the sort of thing you dream up; James, I for one believe you, seeing is believing.

Buy a Fortress or its equivalent :)

Jonathan
 
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Neeves said:
I did some tests on set anchors - upto about 150 degrees anchors will turn in the seabed. beyond 150 degrees they will somersault, land on their back and then need to reset.

It depends on the rate of turn but if your yacht passes beyond that, approx, 150 and then the tension is sufficient - your anchor will somersault.

Set it hard, with a tension higher than the tension the tide might impose - and you should stay where you are/were - otherwise?

Jonathan
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Ok great.

The anchor was well dug in (buried actually) perhaps this is what caused the problem because it didnt have enough height off the seabed for chance of its 40kg weight to drop either right or left to start to dig in because it was already so well buried and had support of the sand as it rotated through 180degrees.

All similar anchors in the sand pit at PYC failed this test: buried then applying a 180 degree horizontal pull. They all just sat up inverted making plough tracks.

Cheers for the info tho!
 
My rotation tests and the upside-down phenomena were 2 different tests, actual the upside down was an accidental test.

The somersault test - I took lots of 15kg anchors and set them (underwater) to 500kg which is quite high, then pulled them at 180 degrees, they all somersaulted. I then set them at a much lower load and pulled at varying angles until I found when they would stop swivelling and only somersaulted (hence the 150 degrees). All the 15kg anchors at 180 degrees, somersaulted, pulled out, dragged with fluke packed with seabed and did not reset until the seabed in the fluke washed out, so they pulled on the seabed surface on their sides - so not inverted and not with the shank 'vertical'. If the seabed had not washed out, had a bit of weed embedded - they might have pulled forever. Anchors like the Spade, Ultra and Excel did not carry seabed and immediately reset. I did not try a Fortress. I was not entirely expecting the results.

This was quite a firm seabed and none of the anchor completely disappeared. If you were testing 40kg anchors and you had them disappear during setting then either you were using a very powerful winch - or the seabed, ground, was very soft.

This underlines why Morgan's Cloud removed their recommendation for a certain anchor, but retains their recommendation for Spade.

Separate occasion, we were testing anchors in very soft sand, same weight of anchor, 15kg. One of them landed upside down it simply dragged forever. The shank was vertical and the fluke sitting upside down in the seabed (bit like a keel or a knife) - so the fluke 'sort of floated' on the top of the soft sand surface. This was found to be common of anchors that demand hard substrate to support the roll bar and top edge of the shank, very many common designs. This was entirely unexpected.

Arguably soft sand and soft mud might be uncommon, or not. Flukes clogging is common.

Most anchors work well in clean firm sand - in peripheral seabeds, where very little testing is conducted - you start to see differences.

No anchor is perfect - all are a compromise.

Your tests sound interesting - you should publish id detail, mine are all in Practical Sailor.

Jonathan

Edit. Most seabeds are relatively well documented and I have not come across a sand seabed in a recognised and named anchorage so soft to cause the problem - but that does not mean they are uncommon. Soft mud is common and is known, at least locally, and so are seabeds where flukes clog. Oyster beds are often indicative of soft muds. close edit.
 
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Neeves said:
Not unusual - Particularly in a soft seabed - this is one reason Fortress are good in soft mud.

Many anchors need a hard seabed to set, think of a roll bar or Delta's roll over shank (that virtually every anchor maker uses - Spade included). They need a hard seabed on which to rest. Turn them upside down and submerge them is something soft, think custard?, or soft sand, mud and they have nothing on which to rest and roll over. Their centre of gravity is too low and they will drag, and drag and drag - until you reach the beach, or somewhere with a harder substate.

I did some tests on set anchors - upto about 150 degrees anchors will turn in the seabed. beyond 150 degrees they will somersault, land on their back and then need to reset.

It depends on the rate of turn but if your yacht passes beyond that, approx, 150 and then the tension is sufficient - your anchor will somersault.

Set it hard, with a tension higher than the tension the tide might impose - and you should stay where you are/were - otherwise?

The idea there is one perfect anchor, a myth put about by anchor makers.

Jonathan
Click to expand...

Hear, hear.

(and believed by the gullible.)
 
Neeves said:
My rotation tests and the upside-down phenomena were 2 different tests, actual the upside down was an accidental test.

The somersault test - I took lots of 15kg anchors and set them (underwater) to 500kg which is quite high, then pulled them at 180 degrees, they all somersaulted. I then set them at a much lower load and pulled at varying angles until I found when they would stop swivelling and only somersaulted (hence the 150 degrees). All the 15kg anchors at 180 degrees, somersaulted, pulled out, dragged with fluke packed with seabed and did not reset until the seabed in the fluke washed out, so they pulled on the seabed surface on their sides - so not inverted and not with the shank 'vertical'. If the seabed had not washed out, had a bit of weed embedded - they might have pulled forever. Anchors like the Spade, Ultra and Excel did not carry seabed and immediately reset. I did not try a Fortress. I was not entirely expecting the results.

This was quite a firm seabed and none of the anchor completely disappeared. If you were testing 40kg anchors and you had them disappear during setting then either you were using a very powerful winch - or the seabed, ground, was very soft.

This underlines why Morgan's Cloud removed their recommendation for a certain anchor, but retains their recommendation for Spade.

Separate occasion, we were testing anchors in very soft sand, same weight of anchor, 15kg. One of them landed upside down it simply dragged forever. The shank was vertical and the fluke sitting upside down in the seabed (bit like a keel or a knife) - so the fluke 'sort of floated' on the top of the soft sand surface. This was found to be common of anchors that demand hard substrate to support the roll bar and top edge of the shank, very many common designs. This was entirely unexpected.

Arguably soft sand and soft mud might be uncommon, or not. Flukes clogging is common.

Most anchors work well in clean firm sand - in peripheral seabeds, where very little testing is conducted - you start to see differences.

No anchor is perfect - all are a compromise.

Your tests sound interesting - you should publish id detail, mine are all in Practical Sailor.

Jonathan

Edit. Most seabeds are relatively well documented and I have not come across a sand seabed in a recognised and named anchorage so soft to cause the problem - but that does not mean they are uncommon. Soft mud is common and is known, at least locally, and so are seabeds where flukes clog. Oyster beds are often indicative of soft muds. close edit.
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Alvor - just watch them dragging down the Ria. Lovely slurpy mud on hard clay!!!
 
When the Bruce first came out, they had little model ones and sandpits one could play with at the Earls Court boat show; the thing re-sets itself very quickly if pull is reversed.

My 7.5kg one has proved the same in real life, but I realise it's not trendy now so can't work; probably would if I paint it dayglo next time I'm aboard. :)
 
Seajet said:
When the Bruce first came out, they had little model ones and sandpits one could play with at the Earls Court boat show; the thing re-sets itself very quickly if pull is reversed.

My 7.5kg one has proved the same in real life, but I realise it's not trendy now so can't work; probably would if I paint it dayglo next time I'm aboard. :)
Click to expand...

They must have had better test anchors, here at PYC the Bruce did the same plough.

I'll double check tomorrow tho.

Thanks Neeves, great explanation. Was it a university project?
 
bigwow said:
I've bought a Fortress, still trying to understand how something this light will hold better than my trusty CQR?:cool:
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Thank you for purchasing our product and we are very confident that it will provide you with many years of dependable, superb performance. The two large precision-machined flukes of the Fortress should result in the anchor burying deeper and providing more resistance to breaking free, versus an anchor with a single, narrow fluke.

During the extensive Chesapeake Bay soft mud testing, it was observed that fixed fluke anchors had difficulty orienting into the fluke downward position if they landed on their side or upside down as they were being slowly pulled through the soft mud. In many cases they achieved only a minimal increase of resistance.

With a pivoting fluke anchor (ex: Danforth-type) there is no upside down position, so that is a clear advantage for this type of anchor.

If an anchor is "flipped over," so to speak, or inverted after it has been well-set and it has soil tightly-compressed against its fluke(s), then the anchor is obviously going to have difficulty re-engaging the sea bottom until the soil is removed.

I certainly agree with the assessment that no anchor is perfect in all sea bottom conditions and that they all have compromises / trade-offs.

Safe anchoring,
Brian
 
Fortress Anchors said:
Thank you for purchasing our product and we are very confident that it will provide you with many years of dependable, superb performance. The two large precision-machined flukes of the Fortress should result in the anchor burying deeper and providing more resistance to breaking free, versus an anchor with a single, narrow fluke.

During the extensive Chesapeake Bay soft mud testing, it was observed that fixed fluke anchors had difficulty orienting into the fluke downward position if they landed on their side or upside down as they were being slowly pulled through the soft mud. In many cases they achieved only a minimal increase of resistance.

With a pivoting fluke anchor (ex: Danforth-type) there is no upside down position, so that is a clear advantage for this type of anchor.

If an anchor is "flipped over," so to speak, or inverted after it has been well-set and it has soil tightly-compressed against its fluke(s), then the anchor is obviously going to have difficulty re-engaging the sea bottom until the soil is removed.

I certainly agree with the assessment that no anchor is perfect in all sea bottom conditions and that they all have compromises / trade-offs.

Safe anchoring,
Brian
Click to expand...

As will the Danforth - though more difficult to handle.
 
bigwow said:
I've bought a Fortress, still trying to understand how something this light will hold better than my trusty CQR?:cool:
Click to expand...

Its not about weight, as such, but surface area and design..

I think if you could make an identical copy of a Fortress, in terms of size, sharpness of the fluke etc, but out of steel it would weight roughly twice as much but it would perform indistinguishably from a Fortress.

Without encouraging Noelex but I cannot distinguish between my steel and alloy Excels (they are the same size) and my steel and alloy Spades (which are also the same size). The alloy versions weigh at 8kgs the steel ones 15kg.

We tend to get hung up about weight - because in general (and traditionally) anchors are 'heavy' and we need to adjust our thinking.

One comment of Fortress is that after a strong wind event they can be difficult to retrieve, because they have set so deeply (and after named storms can be irretrievable (but better that than lose your yacht) I don't think this happens quite so often with CQRs.

Jonathan
 
Jamesuk said:
They must have had better test anchors, here at PYC the Bruce did the same plough.

I'll double check tomorrow tho.

Thanks Neeves, great explanation. Was it a university project?
Click to expand...


I think 'clogging' is a function of the seabed - in good clean sand all anchors work well (or I think they all do). They still somersault but don'r clog so reset almost immediately. The only variation was the SARCA and Supreme using the tripping slot - they pulled out back wards, as they are designed to do - but then took time (space) to reorientate themselves (have the shackle slide back down to the shackle end of the shank). Not a big issue - but maybe an extra 1 metre. They also pulled out at about 130 degrees rather than 150 degrees - so not so dependable as having the shackle at the end of the shank.

I did not test a Bruce, not because I have any dislike - but I do not have a genuine Bruce, you cannot buy a new genuine one and its difficult enough testing a range of 15kg anchors without testing some that no-oe can buy any more. I tested, Spade, Excel, Rocna, Supreme, SARCA. Each was tested within a couple of feet of each other, underwater, none crossed the path of each other - though it was close. So 500kg set, reversed (180 degree) pull, and then pulled until reset. The work was for Practical Sailor in America.

Jonathan
 
This thread is a troll.

Yes, all anchors can flip. However, I think it is obvious the test was in some way false, because in sand they would all reset.

The most probable reason is related to the difference between dry and wet sand, and what was under the sand. I have done lots of testing in dry sand for the purpose of photographs only. The results are actually mostly useless. Can you run wet sand through an hourglass? Of course not. Do any real soils have zero cohesion? No. The behavior in wet bottoms of all types is very different.
 
I basically agree, sand - especially a sandpit for model anchors - is in some ways an unfair testing medium as it's so consistent - though a bit ' thin ' on grip.

I very rarely anchor on sand, though when I have, including in gales, the Bruce has performed faultlessly - it's all nice soft mud around here which certainly gives me more confidence in any anchor, I sometimes crew a boat with a Rocna which seems a perfectly good anchor - though in that particular case, deck stowed on a Centaur, the thing is a pig of a job to get between the forestay and pulpit legs, it's like a metal puzzle !
 
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